IM2000 and Unsolicited Bulk mail

the unsolicited and bulk qualities of mail are
actually directly recognisable in some way,
or

recipients no longer bear the costs of receiving and storing
unwanted mail.

IM2000 incorporates the latter, by redesigning the mail system as a pull
delivery rather than as a push delivery system. (There are
other ways of achieving the goal, too, but they have problems with the cost
of enforcement.) Senders bear the costs of storing the mail that they
send.

IM2000 does not directly incorporate direct recognition of
unsolicited and bulk qualities. Instead it
eliminates part of the very concept of bulk mail by employing an
architecture whereby multiple copies of messages, even of messages sent to
many recipients, do not actually exist in the first place until the
recipients actually request the senders to make them.